1. Technical Field
Various embodiments of the inventive concept relate to a method of fabricating a semiconductor device, and more particularly, to a method of fabricating a phase-change random access memory device (PCRAM).
2. Related Art
As an integration degree of semiconductor devices is increased, a channel length of a transistor is increasingly reduced.
With the rapid development of mobile and digital information communication and consumer-electronic industry, studies on existing electronic charge controlled-devices are expected to encounter the limitation. Thus, new functional memory devices of the new concept other than the existing electronic charge devices need to be developed. In particular, next-generation memory devices with large capacity, ultra-high speed, and ultra-low power need to be developed to satisfy demands on large capacity of memories in main information apparatuses.
Currently, variable resistive memory devices using a resistance device as a memory medium have been suggested as the next-generation memory devices, and phase-change random access memories (PCRAMs), resistive RAMs (ReRAMs), and magentoresistive RAMs (MRAMs) are typically used as the variable resistive memory devices.
The variable resistive memory devices may be basically configured of a switching device and a resistance device and store data “0” or “1” according to a state of the resistance device.
In particular, the PCRAMs may include a phase-change material having a characteristic switched between different resistance states through stabilization to any one of a crystalline state and an amorphous state by a heat. The phase-change material may be a chalcogenide-based material such as germanium-antimony-tellurium (Ge—Sb—Te: GST).
The phase-change material has a volatile characteristic, and thus when the phase-change material is exposed, the phase-change material may be lost through the exposed portion.
In the related art, when a phase-change material layer is etched back, and then an upper electrode is formed, the phase-change material layer is left on sidewalls of a hole since the etching process is not smoothly performed on the phase-change material layer. The phase-change material layer may be lost due to the left portion of the phase-change material layer on the sidewalls of the hole.
Therefore, there is a need for a method of preventing a phase-change material from being lost in recent semiconductor devices.